1. Field of the Invention
This invention relates to a semiconductor device constructed by mounting a semiconductor chip on a carrier tape by the TAB (tape automated bonding) method and to a method of manufacturing this type of semiconductor device.
2. Description of the Related Art
FIGS. 16A and 16B respectively show in plan and in section the structure of a carrier tape on which a semiconductor chip is mounted. The carrier tape has a film 1 formed of an insulating material such as polyimide. A plurality of perforation holes 6 are formed at equal intervals along each edge of the film 1, and a rectangular center device hole 3 in which a semiconductor chip 2 is placed is formed centrally between the edges of the film 1. A plurality of outer lead holes 5 are formed around the center device hole 3. A plurality of leads 4 formed from copper are fixed on the film 1. The leads 4 are supported on a support portion 7 formed between the center device hole 3 and the outer lead holes 5 in such a manner that their extreme end portions extend as inner leads 4a over the center device hole 3 while their central portions are located on the outer lead holes 5 as outer lead 4b to be connected to an external circuit. A test pad 4c is formed at the distal end of each lead 4. The support portion 7 is connected to the major portion of the film 1 by bridge portions 8 positioned between the adjacent outer lead holes 5.
As shown in FIG. 16B, bump electrodes 21 of the semiconductor chip 2 are connected to the inner leads 4a of the leads 4 inside the center device hole 3 of the carrier tape. The carrier tape and the semiconductor chip 2 constitutes a tape carrier.
The thus-constructed tape carrier is embedded in a resin package or the like to protect the semiconductor chip 2 and the leads 4 against external forces and the environment. For example, as shown in FIG. 17A, the tape carrier is set between an upper mold part 10a and a lower mold part 10b. At this time, the tape carrier is positioned so that the semiconductor chip 2 is accommodated inside a cavity half 12b of the lower mold part 10b. The upper mold part 10a and the lower mold part 10b are thereafter clamped, and a resin 11 is injected into the cavity defined by a cavity half 12a of the upper mold part 10a and the cavity half 12a of the lower mold part 10b. After setting of the resin 11, a molded piece such as that shown in FIG. 17B is removed form the upper mold part 10b and the lower mold part 10b. The leads 4 are thereafter cut between the outer leads 4b and the test pads 4c together with the bridge portions 8 of the film 1, thereby forming the semiconductor device.
However, since the semiconductor chip 2 is supported by the thin leads 4 alone at the time of resin molding, the semiconductor chip 2 may shift from the correct position in response to the resin injecting pressure. In consequence, there is a risk of part or the whole of the lower surface of the semiconductor chip 2 being exposed as shown in FIGS. 18A and 18B or a risk of the semiconductor chip 2 being inclined in the resin 11 as shown in FIG. 18C, defects which cannot be found before the molded piece is removed from the mold. Such a shift from the correct position increases the possibility of permeation of water from the outside into the package and reduces the mechanical strength of the package against external forces, resulting in a deterioration in the reliability of the semiconductor device.
If the thickness of each of layers of resin 11 formed over and under the semiconductor chip 2 is increased in order to prevent this defect, the advantages of the TAB method that resides in a reduction in the overall thickness is not effectively utilized.